Aluminum rf connector and method for making same

ABSTRACT

An RF component of the aluminum body, silver faced connector type for use in salty environments is of generally cylindrical configuration, and hard anodized over its entire exposed face to a predetermined depth. A generally cylindrical insert sleeve of brass is silver plated, over its entire exposed face, in a predetermined thickness and then press fitted into the hard anodized aluminum component. No electric current can be generated between the dissimilar metals, even in a slat environment, because of the isolation of the aluminum within its anodized surface. Defects in any rubber end caps and pores developing in the silver plate still prevent salt air from reaching the aluminum.

United States Patent Overh0lser [54] ALUMINUM RF CONNECTOR AND METHOD FOR MAKING SAME [58] Field of Search ..339/l14, 278 D, 278 C, 143, 339/l46, 115

[56] References Cited UNITED STATES PATENTS 10/1958 Chance, Jr. 2.339/278 C X 5/1961 Chess ..339/89 C Aug. 8, 1972 Primary Examiner-Richard E. Moore Attorney-Pearson & Pearson [57] ABSTRACT An RF component of the aluminum body, silver faced connector type for use in salty environments is of generally cylindrical configuration, and hard anodized over its entire exposed face to a predetermined depth. A generally cylindrical insert sleeve of brass is silver plated, over its entire exposed face, in a predetermined thickness and then press fitted into the hard anodized aluminum component. No electric current can be generated between the dissimilar metals, even in a slat environment, because of the isolation of the aluminum within its anodized surface. Defects in any rubber end caps and pores developing in the silver plate still prevent salt air from reaching the aluminum.

8 Claims, 10 Drawing Figures BACKGROUND OF THE INVENTION Radio frequency components, such as connectors of the type disclosed herein, are used in planes of the armed services, usually inside the structure, and are often continuously exposed to the salt air environment of seacoast bases, aircraft carriers, etc. in war areas. The RF connectors presently in use are generally hol low cylindrical in configuration and of aluminum there being a plating of silver on the inner cylindrical face, applied directly on the aluminum. The outer face of the aluminum connector is hard anodized, in compliance with United States Government specifications, and the two opposite, open ends of the connector are closed by rubber caps intended to hermetically seal the silver plated inner face against the elements.

However, it has been found that despite precautions, leaks occasionally develop in the cracks between the rubber caps and the unanodized aluminum ends of the connectors and that the silver plating is not entirely free of pores, whereby salt air gains access to the silver plated aluminum inner face of the connector. A miniature electric battery is thus formed of two dissimilar metals which rapidly tends to deteriorate the aluminum until the RF connector becomes defective, and eventually useless.

DESCRIPTION OF THE PRIOR ART The problem of dissimilar metals has been approached in many patents, but usually the effort has been to continue to have a good electrical, conductive, contact with an aluminum connector body while avoiding inter-action of dissimilar metals.

In U.S. Pat. No. 2,192,751 to Melchoir of Mar. 5, 1940 a thin sleeve of copper is soldered on the inner face of a cylindrical aluminum holder to render the inner face impervious to air, but the remainder of the holder is exposed to the air.

In U.S. Pat. No. 2,901,723 to Kolb ofAug. 25, 1959, the deterioration of aluminum in a salt atmosphere is recognized and the aluminum made extra thick enabling it to be sacrificed for protecting other aluminum parts.

In U.S. Pat. Nos. 2,806,215 and 2,815,497 to Redslob, battery action is avoided between copper and aluminum by plating the aluminum with tin. In U.S. Pat. No. 2,868,863 to Cook, the copper is plated with aluminum and all joints coated with Neoprene.

SUMMARY OF THE INVENTION In this invention, the object is not to promote electric conductivity through aluminum connectors, but rather to avoid such conductivity in a silver faced aluminum RF connector, caused by the battery action of dissimilar metals in a salt environment.

Rather than applying a silver plating to the inside face, hard anodizing the outside face and rubber capping the end faces of a cylindrical, RF connector, the connector of this invention comprises a generally cylindrical, aluminum body which has been hard anodized over its entire inner, outer and end faces to a predetermined depth preferably of between 0.001 and 0.005 inches in thickness. The silver inner face is obtained by forming a brass insert sleeve and silver plating the entire inner, outer and end faces thereof to a predetermined thickness of about 0.0001 inches. The silver plated sleeve is then afiixed within the hard anodized aluminum body of the connector, preferably with a press fit, so that it lines the inner face of the connector. Thus there are no exposed aluminum faces on the RF component which can be reached by salt air, the aluminum being electrically isolated by the hard anodized layer which inhibits further oxidation.

BRIEF DESCRIPTION OF DRAWING 1n the drawing:

FIG. 1 is a side elevation and FIG. 2 is an end elevation, partly broken away, and showing the aluminum body of the component.

FIGS. 3 and 4 are views similar to FIGS. 1 and 2, showing the hard anodized surface of the body.

FIG. 5 is a side elevation and FIG. 6 an end elevation, partly broken away, of the metal insert sleeve.

FIGS. 7 and 8 are views similar to FIGS. 5 and 6 showing the silver plating on the metal sleeve, and

FIG. 9 is a side elevation, and FIG. 10 an end elevation, partly broken away, and showing the completed RFcomponent with its insert sleeve press fitted into its aluminum body.

DESCRIPTION OF PREFERRED EMBODIMENT As shown in the drawing, the RF component 20 of the invention, which is an RF connector, includes a generally cylindrical, tubular body 21, of aluminum 22 having an outer face 23, which is usually generally cylindrical although it may have polygonal faces not shown for application of a wrench. Aluminum body 21 also includes a pair of opposite, open ends 24 and 25 encircled by annular end faces 26 and 27 and includes a generally cylindrical inner face 28 which usually includes the end shoulder flange 29.

The first step in the method of the invention is the hard anodizing of the aluminum body 21, to a predetermined depth to form the hard anodized zone, or layer, 31, on the entire exposed area of the faces 23, 26, 27 and 28 to thereby form a protective barrier to further oxidation. Hard anodized layer 31 is preferably of predetermined thickness, in the range of about one mil to about five mils, this corresponding to from about 0.001 inches to about 0.005 inches. Apparatus for accomplishing such hard enodizing by dipping in an immersion tank is commercially available, well known and, for example, may be of any of the types listed under hard anodizing in Thomas Register of American Manufacturers.

This invention, therefore, includes the formation of an insert sleeve 33, of metal, preferably brass 34, and the method includes the silver plating of the entire sleeve including the outer cylindrical face 35, the inner cylindrical face 36 and the annular end faces 37 and 38 to form a layer 39 of silver of predetermined thickness. The insert sleeve 33 is described as generally cylindrical but it will be seen that it may have an inner integral portion 41, of reduced diameter, for forming a shoulder 42 against which other elements of the component may be seated, such elements forming no part of this invention. The predetemiined thickness of the silver plating, or layer, 39 is preferably only about one tenth of a mil,

or 0.0001 inches so that the silver plating 39 is only about one tenth the thickness of the hard anodized layer 31 on the aluminum body 21.

The final step in the method of the invention is the affixing of the silver-plated, insert sleeve 33 within the hard anodized aluminum body 22, preferably with a press fit, so that the sleeve 33 lines the inner face 28 as shown in FIGS. 9 and 10. It will be seen that even if the silver plating 39 has pores, or even if the rubber caps shown in dotted lines at 44 and 45, do not fit or become brittle and leak air, there is no opportunity for salt air to reach the aluminum 22 and cause deteriorating battery action between the dissimilar metals, aluminum 22, brass 34 or silver 39.

What is claimed is:

l. A radio frequency connector, for use in a seacoast, salt air environment and of the aluminum body, silverfaced, type said connector comprising:

a generally tubular hollow cylindrical body of aluminum, having a generally cylindrical inner face an outer face, and opposite end faces;

a hard anodized layer of predetermined thickness forming the entire exposed surface of said body, including said cylindrical outer and inner faces and said end faces, and isolating all of the exposed faces of said aluminum from further oxidation;

a generally tubular cylindrical insert of brass, sleeved within said body and lining the said cylindrical inner face thereof, but isolated therefrom by said hard anodized layer therein said insert having a generally cylindrical inner and outer face, and opposite end faces;

and a silver plating of predetermined thickness on said insert, said plating forming the entire exposed surface of said insert and covering said opposite end faces and said inner and outer cylindrical faces of said insert,

whereby said aluminum and silver are electric conductively isolated from each other to avoid generation of current therebetween in said salt air atmosphere which might tend to deteriorate said connector.

2. A radio frequency connector as specified in claim 1 wherein:

said hard anodized layer thickness is in the range of about one mil to five mils.

3. A radio frequency connector, as specified in claim 1 wherein:

said silver plating thickness is about one-tenth of a mil in thickness.

4. A radio frequency connector as specified in claim 1 wherein:

said hard anodized layer is about 0.001 to 0.005 inches in thickness and said silver plating is about 0.0001 inches in thickness.

5. A radio frequency connector as specified in claim 1 wherein:

said silver plating is about one-tenth the thickness of said hard anodized layer. 5 6. A radio frequency component for use in a salty environment, said component comprising:

a generally, hollow, cylindrical body of aluminum, said body having a hard anodized surface of predetermined thickness completely covering all sleeve, press-fitted within said body, said sleeve having a layer of silver in a predetermined thickness completely covering all of the exterior faces thereof;

whereby the aluminum of said body is protected from further oxidation, and electrically insulated from said silver, to prevent generation of current due to inter-action of dissimilar metals in said salty environment.

7. A process for making a radio frequency connector of an aluminum body having a silver facing by means of a metal insert sleeve, which comprises the steps of;

forming said aluminum body into a generally, hollow,

cylindrical configuration.

hard anodizing the entire exposed outer, end and inner faces of said body to a uniform predetermined depth, at least 1 mil in thickness,

separately silver plating, the entire exposed outer,

end and inner surfaces of said metal insert sleeve to a uniform, predetermined thickness, at least one-tenth of a mill in thickness, and then affixing said silver plated insert firmly within said hard anodized aluminum body to form a connector free of electrical deterioration from inter-action of dissimilar metals in salty environments. 8. The method of protecting a silver faced aluminum RF component of generally cylindrical configuration 40 from deterioration in salt-containing environments,

said method comprising the steps of,

plating a generally cylindrical sleeve with a relatively thin coating of silver to a predetermined depth to entirely enclose the same in a silver coating;

separately hard anodizing the entire exterior face of said aluminum component to a depth at least twice the depth of said silver coating, by immersion to entirely enclose the same in a hard anodized coatmg,

and then afiixing said silver plated sleeve within said hard anodized aluminum component so that said sleeve lines the inner cylindrical face thereof, but no electrical interaction takes place between the dissimilar metals, silver and aluminum.

Patent'No. 3,683,33l Dated August 8, 1972 lnventofl John S. Overholser It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

This patent was assigned prior to issuance to:

Aeronics Corporation of America Chelmsford, Mass.

In the Abstract, line 10, "slat". should be "sa1t".

Signed and sealed this 24th day of April 1973..

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT QOTTSCHALK Attesting Officer Commissioner of Patents FORM Do-1050 (10769) USCOMM-DC 60376-P69 v: u.s. GOVERNMENT PRINTING omcs I969 o-sss-au 

2. A radio frequency connector as specified in claim 1 wherein: said hard anodized layer thickness is in the range of about one mil to five mils.
 3. A radio frequency connector, as specified in claim 1 wherein: said silver plating thickness is about one-tenth of a mil in thickness.
 4. A radio frequency connector as specified in claim 1 wherein: said hard anodized layer is about 0.001 to 0.005 inches in thickness and said silver plating is about 0.0001 inches in thickness.
 5. A radio frequency connector as specified in claim 1 wherein: said silver plating is about one-tenth the thickness of said hard anodized layer.
 6. A radio frequency component for use in a salty environment, said component comprising: a generally, hollow, cylindrical body of aluminum, said body having a hard anodized surface of predetermined thickness completely covering all of the exterior faces of said body, and a generally hollow, cylindrical, metal insert sleeve, press-fitted within said body, said sleeve having a layer of silver in a predetermined thickness completely covering all of the exterior faces thereof; whereby the aluminum of said body is protected from further oxidation, and electrically insulated from said silver, to prevent generation of current due to inter-action of dissimilar metals in said salty environment.
 7. A process for making a radio frequency connector of an aluminum body having a silver facing by means of a metal insert sleeve, which comprises the steps of; forming said aluminum body into a generally, hollow, cylindrical configuration. hard anodizing the entire exposed outer, end and inner faces of said body to a uniform predetermined depth, at least 1 mil in thickness, separately silver plating, the entire exposed outer, end and inner surfaces of said metal insert sleeve to a uniform, predetermined thickness, at least one-tenth of a mill in thickness, and then affixing said silver plated insert firmly within said hard anodized aluminum body to form a connector free of electrical deterioration from inter-action of dissimilar metals in salty environments.
 8. The method of protecting a silver faced aluminum RF component of generally cylindrical configuration from deterioration in salt-containing environments, said method comprising the steps of, plating a generally cylindrical sleeve with a relatively thin coating of silver to a predetermined depth to entirely enclose the same in a silver coating; separately hard anodizing the entire exteRior face of said aluminum component to a depth at least twice the depth of said silver coating, by immersion to entirely enclose the same in a hard anodized coating, and then affixing said silver plated sleeve within said hard anodized aluminum component so that said sleeve lines the inner cylindrical face thereof, but no electrical interaction takes place between the dissimilar metals, silver and aluminum. 